Add possibility to sort statistics like "visits by server time" by label

[tsteur]

Suggested by users via email:

If you call up the statistic via "visits by server time", "visits by local time" or "visits by day of week" you can not sort it in a different order. Maybe I haven't found it...?!

It is always sorted by the most visits, top/down. I would like to sorted it via time or weekday. In that way I can see exactly when is the peek of the day or of the week.

and Forum:

http://forum.piwik.org/read.php?3,87233

[tsteur]

Needs API improvement. API should tell how report should be displayed.